1. Field of the Invention
The present invention relates to a machine tool for machining a workpiece by advancing and retracting the workpiece toward and away from a tool spindle in a direction along with a rotational axis of the tool spindle. More particularly, the present invention relates to workplece feed mechanism of a machine tool having a pair of guideways for advancing and retracting the workpiece in a horizontal direction along a rotational axis of the tool spindle. Further, the present invention relates to a cover apparatus for preventing from spattering cutting chips, coolant and the like for a machine tool.
2. Description of the Related Arts
A conventional machine tool will be explained hereinafter with reference to FIGS. 1 and 2 basically corresponding to that disclosed in U.S. Pat. No. 4,673,076.
In such a conventional machine tool, a column 214 is mounted on a bed 230, which is movable in an X-axis direction along a pair of guide rails 216 by a motor 215. In the front of the column 214, there is provided a tool spindle 221 being movable in a Y-axis direction along a pair of guide rails 223 by a motor 222. A worktable 211 is arranged on the bed 230 and in the front of the column 214, which is moved in a Z-axis direction along a pair of guide rails 213 through a ball screw (not shown) by a motor 212.
A pallet changer 205 is arranged on the bed 230 and in the front of the worktable 211, in which a pallet 207 mounting a machined workpiece is changed to a pallet mounting a yet unmachined workpiece by rotating the pallet changer 205 at 180 degrees.
As shown in FIG. 2, the guide rails 213 and the ball screw are covered by a telescopic cover 203 that has a peaked portion in the middle thereof. With this construction, since the guide rails 213 and ball screw are covered by the telescopic cover 203, even though cutting chips are generated when the workpiece mounted on the pallet 207 is machined by a tool (not shown) attached to an end portion of the tool spindle 221, the guide rails 213 are not begrimed by the cutting chips. In such a construction, there is an advantage in that a worktable feed mechanism for moving the workpiece can be also used for the pallet changing operation.
A pair of cutting chip exhaust grooves 231 are formed outside of the pair of guide rails 213 and on the bed 230. Generally outside of the exhaust grooves 231, there are provided a pair of cutting chip splash preventing covers 201 extending from the front of column 214 to the worktable 211. A slide door 204 is provided at a right side of the preventing cover 201 in which the maintenance of the tool spindle can be carried out by opening the slide door 204.
The preventing cover 201 is outwardly expanded close to a portion where the machined workpiece is mounted on the pallet 207, which is connected with an entire cover 200 having a half-round shape in the cross-sectional plane thereof for covering the bed 230 and the pallet 208 mounting the not-machined workpiece.
A revolving door 209 is arranged so as to rotate with the pallet changer 205 around a rotational axis thereof. Both end portions of the revolving door 209 are closely faced with both protruding portions 200a arranged at end portions of the entire cover 200, respectively. Therefore, the pallet 208 on which the not-machined workpiece is mounted is separated from the machining area by the revolving door 209.
Thus, the machining area that the tool spindle 221 moves in the machining operation is separated by the preventing covers 201 and the revolving door 209, so that the cutting chips generating in the machining operation are impounded within the machining area thereby. In this situation, the cutting chips drop into the exhaust grooves 231 together with coolant, thereby being exhausted to the front or back of the machine tool by a coil conveyer (not shown) and the like.
However, since the cutting chips drop onto the telescopic cover 203 from the tool attached with the tool spindle 221, the cutting chips heap onto the telescopic cover 203, whereby it is disadvantageous that the cutting chips on the telescopic cover 221 cannot be removed perfectly.
Further, in another conventional machine tool as disclosed in Japanese Patent Publication No. 60-23935 (KOKOKU), there is provided a cutting chips collection device in a bed so as to position under a slide type cover mechanism for covering a feed screw. With this construction, cutting chips from a machining point can be directly heaped onto the cutting chips collection device and however, it is disadvantageous that a part of the cutting chips are left on the slide cover mechanism.